High-scoring games only part of Big 12's defensive story
The incessant knock against the Big 12 this fall has been that the conference doesn't play defense. According to FPI, that criticism is vastly overstated.
It's not that the teams in the Big 12 play the best defense or that the conference has stout units across the league. The Big 12 just isn't the worst at it -- not in the Power 5 -- and other conferences seem to skate by for their respective weaknesses by comparison.
One way to make this comparison is to look at the average Football Power Index (FPI) ratings for every defense in a conference, which at this point in the season are largely based on performance in previous games given the strength of the opponents faced. It's an objective measure of team or unit strength, and is expressed in points relative to the average FBS team per game. So if we want to know how good the average defense is in the Big 12, FPI is the stat to ask. As of Tuesday, here are the average FPI ratings for every FBS conference.
FBS conference defensive ranks
|Conference||Average Defense FPI|
We've been letting the Pac-12 off the hook! The Big 12 has the fourth-best average defense among FBS conferences and is less than 1.3 points per game worse than the vaunted SEC. So while not great, the Big 12's defenses aren't really all that terrible.
By comparison, let's look at how the conferences stack up by average offense FPI.
FBS conference offensive ranks
|Conference||Average Offense FPI|
Look at the Big Ten. Not only is that conference the worst of the Power 5 in offense (and worse in offense than the Pac-12 is on defense), but it also actually ranks below the American Athletic Conference. Yet, there doesn't seem to be nearly the same narrative about the Big Ten lacking offensive firepower compared to what the Big 12 has to put up with on defense.
So why does the Big 12 have its reputation?
One possible explanation is that the conference has had the worst defenses among the Power 5 over the two previous seasons. However, those units were not -- on average -- lacking collectively the way the Big Ten's offenses are now.
Additionally, perhaps the general perception of these conferences is disproportionately shaped by the best overall teams in those conferences. If that's the case, it might hurt the view of the Big 12. Because if we look at just the three best overall FPI teams in each conference, the Big 12 does rank last in defense. That's based on Oklahoma, TCU and Oklahoma State though. If we look at only the three best overall teams in the Big Ten, it actually ranks second-best among Power 5 conferences in offense. And so those teams, most notably Ohio State and Penn State, perhaps are skewing the narrative around the Big Ten and obfuscating the fact that the conference as a whole frankly is not good on offense.
It's important to distinguish between a conference's level of play at the top and overall because conference reputations are often thrown around in evaluations of top teams. The fact that Oklahoma, for example, had to face Big 12 teams does not necessarily mean the Sooners faced an overly easy set of defenses while Ohio State may have faced a weaker set of offenses than most imagine. In general, it's better to consider the strength -- on all sides of the ball -- of a schedule overall, but since performance in conference play is something bandied about, we ought to be sure we know which conferences are best at what.
So ease off the defenses of the Big 12. And if you are in the mood to poke holes in conference strength, maybe cast an eye toward the Pac-12's defenses or the Big Ten's offenses.
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